i8 Darwin, and after Darwin. 



shown, by saying that the one sex is anabolic and the 

 other katabolic ? In so far as these verbal statements 

 serve to express what is said to be a general fact — 

 namely, that the female sexual elements are less 

 mobile than the male — they merely serve to re-state 

 this general fact in terminology whichj as the authors 

 themselves observe, is " unquestionably ugly." But 

 in so far as any question of origin or causality is con- 

 cerned, it appears to me that there is absolutely no 

 m£aning in such statements. They belong to the 

 order of merely formal explanations, as when it is said 

 that the toxic qualities of morphia are due to this 

 drug possessing a soporific character. 



Much the same, in my opinion, has to be said of 

 the Rev. G. Henslow's theory of the origin of species 

 by what he terms " self-adaptation." Stated briefly 

 his view is that there is no sufficient evidence of 

 natural selection as a vera causa, while there is very 

 abundant evidence of adjustments occurring without 

 it, first in individual organisms, and next, by inherit- 

 ance of acquired characters, in species. Now, much 

 that he says in criticism of the selection theory is of 

 considerable interest as such ; but when we pass 

 from the critical to the constructive portions of his 

 books and papers, we again meet with the want of 

 clearness in thought between a statement of facts 

 in terms of a proposition, and an explanation of 

 them in those of causality. Indeed, I understand 

 from private correspondence, that Mr. Henslow him- 

 self admits the validity of this criticism ; for in 

 answer to my questions, — " How does Self-adapta- 

 tion work in each case, and why should protoplasm 

 be able to adapt itself into the millions of diverse 



